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- // Copyright 2015 Google Inc. All Rights Reserved.
- //
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // http://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
- package flushfs
- import (
- "fmt"
- "os"
- "sync"
- "golang.org/x/net/context"
- "github.com/jacobsa/fuse"
- "github.com/jacobsa/fuse/fuseops"
- "github.com/jacobsa/fuse/fuseutil"
- )
- // Create a file system whose sole contents are a file named "foo" and a
- // directory named "bar".
- //
- // The file may be opened for reading and/or writing. Its initial contents are
- // empty. Whenever a flush or fsync is received, the supplied function will be
- // called with the current contents of the file and its status returned.
- //
- // The directory cannot be modified.
- func NewFileSystem(
- reportFlush func(string) error,
- reportFsync func(string) error) (server fuse.Server, err error) {
- fs := &flushFS{
- reportFlush: reportFlush,
- reportFsync: reportFsync,
- }
- server = fuseutil.NewFileSystemServer(fs)
- return
- }
- const (
- fooID = fuseops.RootInodeID + 1 + iota
- barID
- )
- type flushFS struct {
- fuseutil.NotImplementedFileSystem
- reportFlush func(string) error
- reportFsync func(string) error
- mu sync.Mutex
- fooContents []byte // GUARDED_BY(mu)
- }
- ////////////////////////////////////////////////////////////////////////
- // Helpers
- ////////////////////////////////////////////////////////////////////////
- // LOCKS_REQUIRED(fs.mu)
- func (fs *flushFS) rootAttributes() fuseops.InodeAttributes {
- return fuseops.InodeAttributes{
- Nlink: 1,
- Mode: 0777 | os.ModeDir,
- }
- }
- // LOCKS_REQUIRED(fs.mu)
- func (fs *flushFS) fooAttributes() fuseops.InodeAttributes {
- return fuseops.InodeAttributes{
- Nlink: 1,
- Mode: 0777,
- Size: uint64(len(fs.fooContents)),
- }
- }
- // LOCKS_REQUIRED(fs.mu)
- func (fs *flushFS) barAttributes() fuseops.InodeAttributes {
- return fuseops.InodeAttributes{
- Nlink: 1,
- Mode: 0777 | os.ModeDir,
- }
- }
- // LOCKS_REQUIRED(fs.mu)
- func (fs *flushFS) getAttributes(id fuseops.InodeID) (
- attrs fuseops.InodeAttributes,
- err error) {
- switch id {
- case fuseops.RootInodeID:
- attrs = fs.rootAttributes()
- return
- case fooID:
- attrs = fs.fooAttributes()
- return
- case barID:
- attrs = fs.barAttributes()
- return
- default:
- err = fuse.ENOENT
- return
- }
- }
- ////////////////////////////////////////////////////////////////////////
- // FileSystem methods
- ////////////////////////////////////////////////////////////////////////
- func (fs *flushFS) StatFS(
- ctx context.Context,
- op *fuseops.StatFSOp) (err error) {
- return
- }
- func (fs *flushFS) LookUpInode(
- ctx context.Context,
- op *fuseops.LookUpInodeOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- // Sanity check.
- if op.Parent != fuseops.RootInodeID {
- err = fuse.ENOENT
- return
- }
- // Set up the entry.
- switch op.Name {
- case "foo":
- op.Entry = fuseops.ChildInodeEntry{
- Child: fooID,
- Attributes: fs.fooAttributes(),
- }
- case "bar":
- op.Entry = fuseops.ChildInodeEntry{
- Child: barID,
- Attributes: fs.barAttributes(),
- }
- default:
- err = fuse.ENOENT
- return
- }
- return
- }
- func (fs *flushFS) GetInodeAttributes(
- ctx context.Context,
- op *fuseops.GetInodeAttributesOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- op.Attributes, err = fs.getAttributes(op.Inode)
- return
- }
- func (fs *flushFS) SetInodeAttributes(
- ctx context.Context,
- op *fuseops.SetInodeAttributesOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- // Ignore any changes and simply return existing attributes.
- op.Attributes, err = fs.getAttributes(op.Inode)
- return
- }
- func (fs *flushFS) OpenFile(
- ctx context.Context,
- op *fuseops.OpenFileOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- // Sanity check.
- if op.Inode != fooID {
- err = fuse.ENOSYS
- return
- }
- return
- }
- func (fs *flushFS) ReadFile(
- ctx context.Context,
- op *fuseops.ReadFileOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- // Ensure the offset is in range.
- if op.Offset > int64(len(fs.fooContents)) {
- return
- }
- // Read what we can.
- op.BytesRead = copy(op.Dst, fs.fooContents[op.Offset:])
- return
- }
- func (fs *flushFS) WriteFile(
- ctx context.Context,
- op *fuseops.WriteFileOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- // Ensure that the contents slice is long enough.
- newLen := int(op.Offset) + len(op.Data)
- if len(fs.fooContents) < newLen {
- padding := make([]byte, newLen-len(fs.fooContents))
- fs.fooContents = append(fs.fooContents, padding...)
- }
- // Copy in the data.
- n := copy(fs.fooContents[op.Offset:], op.Data)
- // Sanity check.
- if n != len(op.Data) {
- panic(fmt.Sprintf("Unexpected short copy: %v", n))
- }
- return
- }
- func (fs *flushFS) SyncFile(
- ctx context.Context,
- op *fuseops.SyncFileOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- err = fs.reportFsync(string(fs.fooContents))
- return
- }
- func (fs *flushFS) FlushFile(
- ctx context.Context,
- op *fuseops.FlushFileOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- err = fs.reportFlush(string(fs.fooContents))
- return
- }
- func (fs *flushFS) OpenDir(
- ctx context.Context,
- op *fuseops.OpenDirOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- // Sanity check.
- switch op.Inode {
- case fuseops.RootInodeID:
- case barID:
- default:
- err = fuse.ENOENT
- return
- }
- return
- }
- func (fs *flushFS) ReadDir(
- ctx context.Context,
- op *fuseops.ReadDirOp) (err error) {
- fs.mu.Lock()
- defer fs.mu.Unlock()
- // Create the appropriate listing.
- var dirents []fuseutil.Dirent
- switch op.Inode {
- case fuseops.RootInodeID:
- dirents = []fuseutil.Dirent{
- fuseutil.Dirent{
- Offset: 1,
- Inode: fooID,
- Name: "foo",
- Type: fuseutil.DT_File,
- },
- fuseutil.Dirent{
- Offset: 2,
- Inode: barID,
- Name: "bar",
- Type: fuseutil.DT_Directory,
- },
- }
- case barID:
- default:
- err = fmt.Errorf("Unexpected inode: %v", op.Inode)
- return
- }
- // If the offset is for the end of the listing, we're done. Otherwise we
- // expect it to be for the start.
- switch op.Offset {
- case fuseops.DirOffset(len(dirents)):
- return
- case 0:
- default:
- err = fmt.Errorf("Unexpected offset: %v", op.Offset)
- return
- }
- // Fill in the listing.
- for _, de := range dirents {
- n := fuseutil.WriteDirent(op.Dst[op.BytesRead:], de)
- // We don't support doing this in anything more than one shot.
- if n == 0 {
- err = fmt.Errorf("Couldn't fit listing in %v bytes", len(op.Dst))
- return
- }
- op.BytesRead += n
- }
- return
- }
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